The present invention relates to an improved air nozzle for use in spraying a stream of material. The spray nozzle is used, for example, as an air cap on a liquid paint spray gun.
Spray nozzles for paint spray guns are known in the art, for example, refer to FIG. 1 of the drawings. Prior art spray caps normally included a center orifice for the discharge of a stream of paint and air. A pair of horns are positioned on opposite sides of the center orifice. Normally, one or more atomizing openings or jets are positioned adjacent the center orifice along or near a center line plane which is perpendicular to another center line plane extending through the air horns. These atomizing openings allow air jets to penetrate and agitate the mixture of air and paint which is being discharged from the center orifice.
The concentrated mixture which is being dispersed from the orifice is then flattened into a relatively long narrow spray pattern by the combined action of auxiliary jets eminating from auxiliary openings and also horn jets eminating from openings in each of the air horns.
It has been found that problems sometimes arise with prior art spray nozzles when the atomizing jets strike the central material air stream. The atomizing jets tend to splash material laterally towards the air horns. The material, for example, paint, is deposited on the horns adjacent to the horn jets and eventually tends to clog these jets.
When this occurs, the spraying operation must be stopped and the spray nozzle removed and replaced. In production line situations, this time is significant. If the spray cap deposition rate, which is normally measured in milligrams/minute can be reduced, the economic benefit is great.
The present improved spray nozzle includes converging air ramps on the horn projections of the spray cap. The converging ramps induce a greater air flow directed towards the center of the spray nozzle. This induced air flow apparently deflects coating particles moving outwardly towards the air horns, greatly reducing undesired paint deposits on the air horns.
It has also been found that if the atomizing air openings are excluded from angular sectors adjacent a center line plane perpendicular to the center line plane extending through the air horns and center orifice, the unwanted deposition of paint is again significantly reduced.
It is therefore the primary object of the present invention to provide an improved spray nozzle which lowers the deposition rate of paint on portions of the nozzle and greatly increases the length of time in which a spray line can be operated prior to shut down for removal, cleaning, or replacement of the spray gun cap.
Further objects of the present invention will be apparent from the following drawings and specification.